Photographic antihalation layer



June 1940- s E. SHEPPARD ET AL 2,203,659

PHOTOGRAPHIC ANTIHALATION LAYER Filed April 12, 1939 EMULSION FIG.3.

TAINING AN ANALOGUE OF MUREXIDE TRANSPARENT SUPPORT OVERC'OAT/NG' LAYER 0E GELATIN CON- TAINING AN ANALOGUE OF MUREXIDE EMULSION TRANSPARENT SUPPORT Samuel E. Sheppard I Robert C. Houck INVENTORS ATTORNEYS ANTI-HAM TION LAYER OEGELATIN co/v- Patented June 4, 1940 ruo'roeaarmc lm'rmmnou LAYER Samuel E. Sheppard and Robert C. llonek, Rochester, N.Y., assignors to Eastman Kodak Comgany, Rochester, N. Y., a corporation of New Application April 12, 1939, Serial No. 267,479

9 Claims.

Thisinvention relates to antihalation layers for photosraphicfilms.

This application is a continuation-impart of our application Serial No. 102,546, filed Septem- We have found that anumber of dyes including analogues of murexide, as well as murexide itself, may be incorporated in gelatin to give a purple-red color such that the gelatin is suitable her 25, 1936. for use as antihalation backings. These dyes 5 The purpose of providing films with antihave the property of discharging readily and halation layers is well known in the photographic completely in ordinary acid fixing baths having art. When a photographic film is exposed, there a pH of about four. v is a tendency for light to be reflected from the The dyes which we use have the general form surface of thefilm support or other layer of the mula: 1m

film and to produce on the sensitive emulsion ox layer, according to its intensity, halos surrounding brighter parts of the image. This efiect is I known as halationand it is customary to coat R the rf Of h pp r w a 001011118 where R and R. represent the atoms necessary to 15 material whichabsorbs the light and prevents a complete a carbocyclic or heterocyclic ring, and reflectiononto the sensitive layer. Where the X represents an alkali metal or alkaline earth film is to be used as a transparency, the coloring radical, such as sodium potassium, or ammonium,

matter designed for antihalation purposes must, or nickeL of course be removedl i The principal compound of this group which 20 It is Obvious that the eolorlns matter used we contemplate using is murexide, which is the this purpose should be removed as completely as ammonium salt of p r ufl acid, and has the possible during processing of the film. Dyes used g n m constitution; for this purpose sometimes have a tendency to V stain the support or other layers 01'- the film and 25 to be retained in the film after processing. Some Z dyes which are readily removed in an alkaline so- 0:0 lution, such as a photographic developer, have a tendency to discolor the developer to such an an extent that it isrendered useless for further de- ONE 0 lo It is desirable to maintain the dev logifi g zolution in a pure condition so t it The color discharge when the gelatin layer dyed may be used to develop large amounts of film. with this compound is sublected an acid Fixmg It is th f an Object f present inven bath is probably associated with the formation of tion to provide an antlhalation layer having a the keto-isomer of purpuric acid which ls decom 35 dye which is readily decolorized in the processing Posed b hydrolysls to anon and P' The baths. It is a further object to provide an antistructure of this compound (Purpunc acid) may halation dye which is removable in an acid solube represented as follows:

tion such as a fixing bath, but not in a developer 0 solution. It is a stillfurther object to provide anew class of antihalation dyes. 40

Ylhese ,objects are accomplished by incorpora- 0==o CEN=C c-=o tion in a gelatin layer, applied to the film, a dye or dyes which are analogues of murexide. 6

We may use murexide itself as well as analogous 45 mmmmldsy and by the term "anahgues Other dyes which we contemplate using are the rexide}! we include murexide itself as well as foll wing: Rubazomc acid; analogous compounds. i

' In the accompanying drawing we have shown 3' a number of enlarged sectional views of photo- Nae G===N' graphic film coated with antihalation dyes ac- I i cording to our invention. Inthe drawing: Fig. 1 is a sectional view of a film having an. O 0

antihalatlon layer on the rear surface of the A Support. Dlketohydrindylidenediketohydrlndamine: 55

Fig, 2 is asectional view of a filmhavlng an antihalation layer between the emulsion layer C0 and the support, and x Fig. 3 is a sectional view of a film having an C30/ \00 go antihalation layer coated over the emulsion layer.

The compound murexide'may be produced by the condensation oi alloxanand uramil in an al-' 'kaline solution in the usual manner. The other compounds listed above may be produced by treating the carbocyclic or heterocyclic nucleus with hydroxylamine.-reducing the oxime formed in this way and condensing the reduction product with the original or a different ring compound. For example, rubazonic acid may be produced by treating 1-phenyl-3-methyl-pyrazooxime formed in this way: e reduction prod- Th uct is then condensed with an' equimolecular amount oi. the original ring compound to proaction may be represented as follows:

, w o Or H din ion. 7

In a similar manner the compound diketohydrindylidenediketohydrindamine is produced by condensing 2 molecules of triketohydrindine; the compound diketohydrindylideneuramil is: 'produced by condensing a molecule of uramil with a molecule of triketohydrindineand the compound diketohydrindylidene-keto-phenylmethyl pyrazolamine is produced by condensing a molemile of 1 phenyl-3-methyl pyrazolamine with a molecule of triketohydrindine. r

It is not known whether these compounds exist in the keto or the enol form in every case, but it ledione with hydroxylamine and reducing the duce rebazonic acid. The equations for this re-- aaoasaa is now understood that there is a virtual tautomerizing or resonance in the chrom'ophore chain which would mean an oscillation between the enolic and ketonic iorms, indicated as follows: Y

\n a! \n/ \n'l The color obtained when an analogue of murex ide is added to gelatin is dependent on several factors, including the ash content of the gelatin,

and the alkali used to adjust the pH 0! the gelatin solution. In general, it may be said that with highash'gelatin, color is produced either in acid or alkaline solution, regardless of the alkali used to adjust the pH. With low ash gelatin, flocculation occurs, especially. in alkaline solution, when the pH is adjusted with a strong inorganic alkali,

while'a uniform color is produced ineither acid or alkaline solution in which the pH is adjusted with an organic alkali.

This is indicated by the following table:

" Acid solution Alkaline solution High ash gelatin. Orange color. Orange color.

Low ash gelatin... Na0H-flocculation.- NaOH-ilooculation.

NHloli-ilooculatiom NECK-purple color. Tricthanolamine- Triethanolamlnepurplecolor.

purple color.

The high ash gelatin may be an original undeashed photographic gelatin containing from 1% to 2% ash. The low ash gelatin may be de- .ashed gelatin originally obtained by lime processing, or an acid processed gelatin, as describedin Sheppard-and Hudson U. 8. Patent No. 2,101,877,

' December 14, 1937. De-ashed or acid processed gelatin usually has an ash content of less than The following examples, which are illustrative only, indicate methods of forming antihalation layers according to our invention:

Example 1 A ouantity of deashed gelatin having an ash content 01 about 0.02% was adjusted to a pH of 7.3 with triethanolamine. Murexide was added in the amount or 1%01' the weight of gelatin solu-' tion, "and the colored mixture coated on a support. The gelatin coating had a reddish-purple color which it retained -on drying, and was suitable form as anantihalation layer.

" l'mmplez i 1.25grams' oi the potassium salt or diketohydrindylideneuramil weredissolved in 50 cc. of

'water, and thls's'olution was added to a solution or 7 grams of deashed gelatin in 50 cc. of water.

the pH of the gelatin solution having been adjusted to8.9 with ammonium hydroxide. This mixture was coated on a glass plate having a cellulose nitrate coating. and permitted to'dry.

'Ihe illm thus formed had a reddish-purple color suitable for use as an antihalation backing.

The antihalation layersmade according to our invention may be used in various ways to coat photographic him. Inthe accompanying drawing wehave shown in Pig. 1 a sectional view of the usual film construction in which II repre-'- 'sents a transparent. support of cellulose nitrate,

cellulose actate or other suitable material coated with an emulsion layer II. On the opposite side of the support" it there is coated a gelatin layer it containing one of the analogues of murexide used according to our invention. Fig. 2 represents another type of film in which the antihalation layer I2 is coated between the support l and the emul- 5 sion layer ll. Fig. 3 represents a further type of film in which the antihalation layer I2 is coated over the emulsion layer H, which is coated on the support HI. This latter type of film is designed for use in exposure of the sensitive emulsion layer through the support, and in this type as well as in the other types of film, it is highly desirable to remove the antihalation layer during the processing of the film. The colored layer may also serve as a filter layer, in which case the emulsion layer is exposed through the colored layer.

It is to be understood that the examples or the dye compounds and the methods of using them incorporated in the above specification are by way of illustration only and that our invention is to be taken as limited only by the scope of the appended claims.

We claim:

1. A photographic element comprising a support, a sensitive emulsion layer thereon, and a layer of unsensitized gelatin thereon uniformly colored with a compound of the general formula:

where R and R represent the atoms necessary to complete a ring structure and X represents an alkali metal radical.

2. A photographic element comprising a support. a sensitive emulsion layer thereon, and a layer of unsensitized gelatin thereon uniformly colored with murexide.

3. A photographic film comprising a transparent support, a gelatino-silver halide emulsion layer on said support, and a layer of unsensitized gelatin on said support containing murexide, the emulsion layer being located betwen the source of exposing light and the unsensitized gelatin layer.

4. A photographic film comprising a transpar- 45 ent support, a sensitive emulsion layer on one side of said support, and on the opposite side of said support a layer of unsensitized gelatin uniformly colored with a compound of the general formula:

ox i wherein R and R represent the atoms necessary to complete a ring structure and x represents an alkali metal radical.

5. A photographic element comprising a transparent support, a gelatino-silver halide emulsion layer on one side of said support, and on the opposite side of said support a layer of gelatin uniformly colored with murexide.

6. The method of forming a photographic antihalation layer which comprises incorporating in gelatin, having an ash content less than about 0.2% and having its pH adjusted with only an organic alkali, a compound of the general formula:

where R and R represent the atomsnecessary to complete a ring structure and X represents an alkali metal radical and coating the solution on a support.

7. The method of forming a photographic antihalation layer which comprises incorporating murexide in gelatin having an ash content less than about 0.5% and having its pH adjusted with only an organic alkali, and coating the solution on a support.

8. The method of forming a non-halation photographic element, which comprises coating on one side of a transparent support a layer of gelatin containing murexide, said gelatin having an ash content of less than about 0.5% and having its pH adjusted with only an organic alkali, and coating a sensitive emulsion layer on the opposite side of said support.

9. A photographic element comprising a support. a sensitive emulsion layer thereon, and a layer of unsensitized gelatin thereon uniformly colored with a compound of the general formula:

where R and R represent the atoms necessary to complete a ring structure and X represents a metal radical selected from the group consisting of alkali metal radicals, alkaline earth radicals,-

and nickel.

SAMUEL E. SHEPPARD. ROBERT C. HOUCK. 

